feat: 调整品牌开屏与纯黑原生启动

lib/pages/home/home_view.dart

@@ -30,6 +30,9 @@ import 'home_logic.dart';
 import 'widgets/home_feed_grid.dart';
 import 'widgets/home_grid_header.dart';
 
+const Duration _startupSplashMinimumDuration = Duration(milliseconds: 400);
+const Duration _startupSplashFadeDuration = Duration(milliseconds: 200);
+
 class HomePage extends StatefulWidget {
   const HomePage({super.key});
 
@@ -41,15 +44,31 @@ class _HomePageState extends State<HomePage> with WidgetsBindingObserver {
   bool _resumeRetryInFlight = false;
   HomeFeedController? _homeFeed;
   bool _recommendSeeded = false;
+  Timer? _startupSplashMinimumTimer;
+  bool _catalogSettled = false;
+  bool _startupSplashVisible = true;
+  bool _startupSplashFadingOut = false;
+  bool _startupSplashMinimumElapsed = false;
+  bool _startupSplashDismissing = false;
+  bool _startupSplashSettledTriggered = false;
 
   @override
   void initState() {
     super.initState();
     WidgetsBinding.instance.addObserver(this);
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      if (!mounted) return;
+      _startupSplashMinimumTimer = Timer(_startupSplashMinimumDuration, () {
+        if (!mounted) return;
+        _startupSplashMinimumElapsed = true;
+        unawaited(_dismissStartupSplashIfReady());
+      });
+    });
   }
 
   @override
   void dispose() {
+    _startupSplashMinimumTimer?.cancel();
     _homeFeed?.dispose();
     WidgetsBinding.instance.removeObserver(this);
     super.dispose();
@@ -83,7 +102,41 @@ class _HomePageState extends State<HomePage> with WidgetsBindingObserver {
   @override
   Widget build(BuildContext context) {
     final catalog = context.watch<CatalogController>();
-    return Theme(data: AppTheme.dark(), child: _buildHome(context, catalog));
+    _catalogSettled = catalog.settled;
+    if (_startupSplashVisible &&
+        _catalogSettled &&
+        !_startupSplashSettledTriggered) {
+      _startupSplashSettledTriggered = true;
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        if (mounted) unawaited(_dismissStartupSplashIfReady());
+      });
+    }
+    return Theme(
+      data: AppTheme.dark(),
+      child: Stack(
+        fit: StackFit.expand,
+        children: [
+          _buildHome(context, catalog),
+          if (_startupSplashVisible)
+            _StartupSplashOverlay(fadingOut: _startupSplashFadingOut),
+        ],
+      ),
+    );
+  }
+
+  Future<void> _dismissStartupSplashIfReady() async {
+    if (!mounted ||
+        !_startupSplashVisible ||
+        _startupSplashDismissing ||
+        !_startupSplashMinimumElapsed ||
+        !_catalogSettled) {
+      return;
+    }
+    _startupSplashDismissing = true;
+    setState(() => _startupSplashFadingOut = true);
+    await Future<void>.delayed(_startupSplashFadeDuration);
+    if (!mounted) return;
+    setState(() => _startupSplashVisible = false);
   }
 
   Widget _buildHome(BuildContext context, CatalogController catalog) {
@@ -109,6 +162,35 @@ class _HomePageState extends State<HomePage> with WidgetsBindingObserver {
   }
 }
 
+class _StartupSplashOverlay extends StatelessWidget {
+  const _StartupSplashOverlay({required this.fadingOut});
+
+  final bool fadingOut;
+
+  @override
+  Widget build(BuildContext context) {
+    return IgnorePointer(
+      child: AnimatedOpacity(
+        key: const Key('startup-splash'),
+        opacity: fadingOut ? 0 : 1,
+        duration: _startupSplashFadeDuration,
+        curve: Curves.easeOut,
+        child: ColoredBox(
+          color: AppColors.appBackground,
+          child: Center(
+            child: Image.asset(
+              'assets/icon/splash_logo.png',
+              key: const Key('startup-splash-logo'),
+              width: 240,
+              fit: BoxFit.contain,
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}
+
 /// 四个根页面共享同一路由并保持各自状态。
 class _HomeTabs extends StatefulWidget {
   const _HomeTabs({super.key, required this.feedController});